I just started using a straight razor as well and found I have run into this issue a few times as well (particularly under the nose). For me this seems to be a combination of angle and razor sharpness. When I got the razor it was professionally honed and I didn't run into this problem, but a few uses later when it started to dull slightly I find I am running into it a bit more often. You shouldn't need to "push through" anything, and I would never suggest pushing through when your razor stops. Simply try attacking that section from a different angle to see if you can get a better cut on it.