I have one website that is consistently getting weird form submissions. It's a contact form that captures name, email, subject, and message. Five to ten times per day it gets a submission where all the fields are filled in, the name and the email appear to be real, but unrelated (e.g., "Tom Jones", and "bob_smith@<major_email_provider>.com), and the subject and message are each one (apparently) random word (e.g., today, one had the subject "infrastructure" and the message "Ball").
Is this some known "attack" (I put that in quotations since at only 5-10 per day, it's clearly not a DOS or something)? Should I care about it? Should I do something about it?