noper. some ladies just have low riding cervix.
some ladies have an inverted cervix.
the bad sex.. arousal naturally relaxes muscles/infuses the pelvic region with blood. the result is lengthening of the vaginal barrel and lifting of the uterus by suspensory tendons and other odd pelvic-y bits. almost like a reverse/innie boner.
but sometimes lady bits are contrary.. and depending on where she is in her cycle the cervix can be low in the playing field and quite tender. if you really wanna learn up on girl parts
BeautifulCervix.com is awesome. graphic & awesome.
bad alignment... is just one peculiarity of anatomy butting up against another quirk of anatomy. say she has an introverted cervix and he's got a sharp upward curve. that can be bad. or, if he's going at wonky angle.. sorta thrust up and in instead of up and back.
Mr. RawDawg has some nifty animations on his website. user search will turn up his profile, links be in the sig line.