Hello ladies! I’m new to charting my BBT while trying to conceive and had a question. Has anyone had a dip in their BBT before they ovulate?

This past week my temps have been 97.02-97.03-97.07-97.05-97.30-97.32 and today, 96.73. Is this normal? I’ve been using Clear Blue Advanced Digital OPK to track my fertile window and ovulation, so I know I haven’t ovulated (tested this morning and it still showed high/flashing smiley). Has this happened to anyone before? Any input is appreciated!!