Clumpy Head

I am having a unique issue with one of my new batches. It is carbonated well and tastes great, and has a great head, but as the head begins to fall, it doesn't seem to fall evenly. There will be patches or clumps of the head that remain on the top of the beer. I'm wondering if it was a lack of a good "head retention" steeping grain like Crystal Malt. Below are my notes from the boil night, so you can see everything I did and how I did it. Like I said, the beer tastes great, it just looks funny after the head falls. Also, it doesn't say it in the notes below, but when I bottled, the FG was 1.020, which brings up another question. This is the 3rd batch in a row that won't seem to have a lower FG. All three batches, which were different styles and recipes, all had an FG of 1.020. Is this an extract thing?

Gravity: Original: 1.060 Expected: ??

6:12PM: Steeped Grains at 158F for 30 minutes in 2.5 Gallons
• .25# Carapils
• .125# Special Roast

6:42PM: Removed grains and brought to a boil for extract addition. Removed from heat and added:
• 2# Briess Bavarian Wheat DME
• 3.3# Pilsen Light LME
Brought back to a boil

7:20PM: Kettle temperature reached boiling, started 60 minute boil timer.
• Added 1oz Palisade Whole Hops, 7.3% for 60min

7:50PM: Rehydrated 1 packet of SafeAle S-04 in 500ml of pre-boiled 78 degree water

8:00PM: Added
• Added 1oz Palisade Whole Hops, 7.3% for 20min
• 4 cups of warm water

8:15 PM: Added
• ½ tsp Irish Moss
• 3.3# Pilsen Light LME

8:20PM: Removed kettle from heat and into ice bath.

9:10PM: Poured wort into fermenter, straining out hops, produced 2.5 gallons. Added just over 2.5 gallons of water, totaling just over 5.gallons at 1.060 at 65 degrees. Aerated, pitched yeast, covered, air locked, and into fermenting closet at 65 degrees for roughly 3 weeks.

It actually looks just like the pic in this thread.

https://www.homebrewtalk.com/f13/clumpy-head-365117/

However, nobody was able to tell him why either.

I just brewed a Belgian Pale that has the same problem. Been looking around for input and I can't seem to scrounge much else up either. While likely unrelated to the other posts about this, I know my BPA had a lacto infection at kegging so I am pretty sure that's where my issue is coming from. Might be something to double check.

This is from after the head fell; glass is at an angle, you can tell it's weird by how the head just sticks together instead of the sides of the glass, near the bottom of the pic:

A thick,rocky head on a beer is thought of as desireable. Look at pics of German beers,for instance.