Calendar has changed help!?!?

Amanda • I`m 31, a wife and mother of a 9 yr old. We have finally been blessed with a pregnancy! Hope it sticks!!
I just started using this app this months, actually a few days after AF. It was showing my fertile window starting yesterday so when I took my first opk this morning it have me the solid smiley face. When I logged my info  it changed my calendar. Has this happened to anyone else? I guess it's a good thing we have been baby dancing every day!