Just as a side note: there are many gays who don't do anal play. It seems that most tend to enjoy blowjobs. Therefore, you could say that:
If enjoying receiving anal play as a man makes you "gay" because gay couples enjoy anal play
AND
gay males also enjoy receiving blowjobs
THEN
enjoying receiving a blowjob is "gay"
See the silliness in the logic?
The big question is how much does it really matter. My sexuality is important to me and my partners, and possibly my doctor in certain instances. Not really important to any other people.
Jack Morin has an interesting thesis presented in his book Anal Pleasure and Health. He surmises that male fear of enjoying anal stimulation is three-parted: fears of the taboo nature of anal play, fears of being "gay", and more hidden (but none the less powerful): fears of feminization. Interesting thought - I wonder what's so scary about women in males' collective unconscious?