Mailchimp Subscriber List

I’ve been using Mailchimp for my newsletters for the past 3 months – via Mailchimp for WordPress plugin.
In the past couple of weeks, my subscriber list increased considerably but majority of the subscribers’ names appear as a number on my list such as 57dc8236c0c7d (instead of their actual names). The subscribe form is working fine on my site so I’m wondering if these are spambots or a glitch from Mailchimp’s end. I tried contacting Mailchimp and googling the issue to no avail.
If anyone had a similar experience and can confirm these would be spambots, I’ll go through my list and delete them.