Sorry to post about my Maltese (this is Yorkietalk, after all) but I'm worried about him.

Codie was neutered at 6 months of age. He's approaching his 2 year birthday and just recently (this past week), I've noticed his little red "pee pee" coming out. It's actually happened a lot this week -- about 12-15 times so far that I or my husband have personally seen -- and who knows how many more time it could have popped out while we were at work. I'm taking him to the vet after work on Friday for a check-up. But before I go, I'd like to have an idea of what I'm dealing with -- I always like to be prepared.
Is this a big medical problem? Could it possibly require surgery? Why is it happening? ANY advice or info at all is greatly appreciate. Also, if you could post some links on the subject (if at all possible), I would truly appreciate.
Thanks so much in advance!