The OG needs to be taken before fermentation starts - that is, before pitching your yeast. If your 1.050 was what your hydrometer read after your beer had fermented for a couple of days, then you might have a stuck fermentation (in other words, your yeast has stopped making alcohol).
If your temp. didn't get below 50 degrees, it should still be working strong...unless you're using Lager yeast, in which case you'll be good well below 50 degrees. Really, we all need some more information to give you a real good answer.
More than likely, you're being a nervous nelly and everything is A-ok. The 1st beer I ever brewed - a dry stout kit - only bubbled for one day and then stopped...and the bubbles weren't anything impressive. It turned out to be over 5% and just fine.
Again, knowing what yeast you used, the temp. you kept it at, and when you took your first hydrometer reading. Godspeed! There's a 97% chance you're totally fine.