mercarb choke plate question

[Degree of Freedom]

About a month ago I rebuilt my carb. At that time all the necessary adjustments were made and the engine ran perfectly. All of a sudden, now the choke plate closes too far. When closed, there should be a 5/64" gap. Instead, it is slamming shut completely, meaning until the engine reaches operation temperature, it won't accelerate past idle without stalling.

Ok, no big deal, make the adjustment and get on with it...but I'm curious what could've caused this? Is there another underlying issue?

Thanks

 

[Island Fish Lifter]

Most times adjustments dont change by themselves, i would have a closer look.