The kit zoom lens 14-42 is really smooth, but a 17 / 1.8 is very tight.
This is a common issue with Olympus bodies and ยต4/3 lenses. In the case of the kit lens, it's mount is made out of some type of plastic, so it has some yield and is somewhat
slippery. The tight fit of lenses with a metal mount appears to be due to a combination of materials, finish and tolerances. I have an EM10 and the mount appears to be chrome plated brass and does not have a fine surface finish. This makes for high friction with a metal mount lens. (My 17/1.8 lens looks like it has very finely machined, high silica content aluminum alloy mount.) My EM1 and EM5 look like they have stainless steel mounts with a much finer (lower RMS) finish. Lenses mount much easier to these cameras. The fact that some people have real problems mounting lenses to a body, but other people with the same body/lens combination don't, suggests tolerances issues. FWIW, I had a Panasonic GX1 body and had no problems with any lens, and I've read about very few, if any problems other people have had with Panasonic bodies.
The lens and body mount eventually bed in and the friction drops. I the meanwhile, you can spray a bit of silicone lube on a cloth and wipe down the face of camera's lens mount.