Did you prime the skimmer after removing it and cleaning it? If you do not prime the skimmer, there could have been air bubbles trapped on the plumbing that could have created an obstruction and reduced the amount of water the skimmer can push out compared to the amount of water the skimmer was taking in.
Also, did you clean the sponges? If not, the sponges inside the skimmer can also obstruct the flow of water causing the skimmer to intake more water than it can push out.
Lastly, if there was any soap or cleaning solution residue in the skimmer, it may have been introduced into the water column and caused the water to intake more air than usual and therefore, caused the skimmer to over bubble and overflow.