Yes, this would be a problem.
You will need to put the unit on something that allows the rubber feet support such that the air flow is not blocked. You can either buy something just for this purpose or make something yourself.
For instance, my local Comp-USA stores have a ventilated plate just for this purpose. It is black and sells for around $10 US. You can also use anything like a small piece of shelving material, plywood, etc. Just cut to fit, paint, laminate your favorite picture on it, etc. Have fun with it!
Lot's of possibilities.