Foamy wort during boil

Hello, Long time follower first time poster. I've brewed dozens of successful batches but today I had a first that I've never encountered and couldn't find any information about. So I'm hoping someone can shed some light on it for me. Today I brewed a basic american light lager, recipe:

4 lbs rahr premium pilsner
3 lbs flaked rice
8 oz carapils
.50 oz hallertau 60 min
.25 oz hallertau 20 min
.25 oz hallertau at flame out
1/2 gallon starter saflager 34/70 (2 packs)

Everything went well during the mash. I hit all of my target temps and drained off 6.5 gallons of tasty wort. I did a single infusion with a batch sparge. On to the boil, I started what I was expecting to be a 60 minute boil but once it came to a boil it started foaming which is normal I know. Usually the foam subsides after a few minutes of boiling but this time it stayed foamy the entire time. I even boiled for an extra 20 minutes to see if the foam would subside but it didn't. I wound up with only 3.5 gallons of wort after the boil, so I had to stretch it with some extra light DME boiled and hopped with .25 oz hallertau. So I chilled it down and pitched my starter and it's in the ferm chamber now at 55 degrees. The wort looks and tastes very good, but I can't help but be afraid that something is wrong because it was so foamy. I'm very mindful of my sanitation so everything is very clean. Any ideas/advice is welcome. Thanks!

Sounds fine to me. Maybe you just had the heat up a little higher or less wort than normal? Still, nothing to worry about.

Thanks for the fast reply! I actually adjusted the heat several times to see if I could get it to stop. I'm wondering if it's the large amount of flaked rice. I've never used that much of any adjunct in any batch. I've never brewed a light lager as it's not my beer of choice but I keep reading about how hard they are to brew proplerly so I felt like it was a challenge I wanted to take.