Same here!
A321 MSN 10xx. For us it happened more during latter stages of flight. Though occasionally I saw it during mid flight on a 5hr sector. Example: TOD we can be showing EFOB 2.5t but starts going down about 0.1t every 5 minutes. When we land we see a figure closer to 2.0t being actual FOB. Refueling figures verify there was no "leak". The system was simply getting it wrong. Reported to engineering who thought I was smoking something (JET A1 probably)