I wouldn't consider anal sex giving or receiving with a woman a gay act per se, I have experienced anal play and anal penetrative sex with a woman, which for me is not as enjoyable as vaginal play/penetration. Anal sex, especially involving the penetration of a woman seems for me by nature a more aggressive act, as would a woman using something to anally penetrate me I guess.
However the love of anal play/sex in the context of hugging and caressing, especially if the inclination or preference is towards some bloke interacting with you that way within a sexual encounter, in other words someone the same gender as me; would begin to make me wonder about how to classify my sexual leanings, even if using a strap-on or sex toy.
Oddly enough it wouldn't raise the same question in my mind if it were woman to woman.. I guess because there one is acting like a man in the accepted traditional sense. Man on man the person on the receiving end has to act as the woman, albeit in a more non traditional sense when it comes to penetration. Can't imagine embracing a man in a sexual context. I love the feel of a woman and so can understand another man or woman feeling the same about it.
Not keen on feeling or caressing another man, so I guess that blocks my ability to empathise, especially as I do see the sex act as purely caring and fluffily sharing a moment, not aggressive, dominating or necessarily masterful. I guess its the different degrees of wiring that living creatures have that make us interesting.