That happened to me a little at first when I started playing online chess but the effect didn't last long. I think it initially confuses the brain. I think I'm actually much better with real pieces now. The 3D depth of a board helps me to see tactics.
In short, I wouldn't worry about it much.
holla zankfrappa! An old friend of mine used to chill with Frank Zappa! Listen I totally relate to isolating for the cause, I've been playing chess like 8 hours a day when I work and more when I don't. I do make it out to my local chess club 1x week. the play there is quite strong and find the first game is always the toughest. It is definately something spacial about 3-d to online. However, fundamentals are well just that. Play a passive opening first just to get used to it and you'll be fine. to many cats stress losing, until I'm at least a 2200 I really don't mind. Just make legal moves and hope for a glorious death!!
I have spent months playing online chess in the hopes of improving my game, I have refused to hang out with mates and totally isolated myself for the cause. I recently took a break and played chess with actual people, I got murdered because moving pieces was too weird. Strange. Im new here and unsure if I want to start playing...