Is this a grammatical error? What type of clause is this?

I’m critiquing a piece of creative writing and the author keeps using a sentence structure over and over. It’s a bit distracting and doesn’t exactly sit right with me, but I’m no English major. I can’t figure out why this bothers me. Here are a few examples:

Cursing loudly, John spilled the hot coffee on his hand.

Fumbling with her keys, Sarah opened the door.

Laughing and joking, the friends gathered around the table.