Depending on when you check it, coolant level can vary a little bit. Coolant level will be higher in the bottle on a cool engine.
Occasionally the only way to fully "burp" a cooling system of all it's air bubbles is to drive it. It could be you have a combination of those two issues. Keep an eye on the coolant level and temp guage for the next few days.

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Fourings

84 Audi Coupe GT with Turbo engine, EFI (buh-bye CIS), Jamex seats, Koni's/H&R's, e-code lights. 210k and counting.
1992 Anthracite 400E, 161k, "Grey Ghost".
1986 VW Quantum Syncro, 192k, gone to the crusher in the sky.
1989 300TE 172k. (Was mine, now also Mom's car)
72 280SE 4.5 (Mom's car)