Watkins struck in their comeback, with Arsenal having a late winner denied through Kai Havertz for a handball.
The Villa centre-forward said afterwards: "Seeing it back I'm not sure, it has gone in favour of us. If it was against me I would be a bit disappointed.
"I don't know. From that angle I am not sure, but that's what VAR is there for.
"I think we got the goal, Luca (Lucas Digne) put in an unbelievable ball and Youri Tielemans scored.
"We got a lot of momentum from that and we had a bit of faith whenever we went forward that they were quite open."
On Arsenal's defence, he added: "We knew they went man to man. There was chances there to be taken as they're always a little bit open. When I got my goal I felt we had enough time to push on and get a goal, but it was about being brave and making more passes.
"First half we went direct - Gabriel is a strong guy, so it is hard to hold the ball up against him."