Toddler rubs his eyebrows

Hi! My son is 4 and for the last 3ish years he rubs his eyebrows. Like a lot. It’s been worse lately. Maybe because I’m pregnant? But I have noticed that he freaks out and starts screaming and trying to get his arms free (like when I’m drying him off after a shower and he is wrapped in a towel) so he can rub his eyebrows then he immediately calms down and is better. Does anyone have any answers or maybe suggestions? Maybe it’ll just go away on its own? Thank you!