I have refilled the coolant reserve tank because it was running low. The tank is now topped up, away beyond the FULL line. Can this cause any problem?

It may spit up some fluid due to the fact that the coolant will expand as the engine reaches operating temp and this expansion may cause it to overflow a bit. If it does burp fluid its not that bad just be sure to wipe it up if you notice it has becasue fluid can be corrosive to some materials such as paint.

I always have mine filled somewhat above the Full mark; as noted, leave plenty of airspace above for expansion liquid from the radiator during driving.