Does the talk count as invited if my PI invited me?

Since you have graduated already I would say that it is perfectly fine to list it as "invited". If the other speakers are able to do so, then you should also. This is especially the case since your use of the CV is for graduate school admission, not some later career stage purpose.

It might be a bit presumptuous to list a ten minute talk as an invited talk if you had just earned a doctorate with this professor, but for someone in your position it is an honor to be asked, even for such a short talk. I'll guess that few such BA/BS students are in a similar position.

However, while the "invited" part seems fine to me, you might want to take care about how you state the rest of the description. "Invited talk" might imply more than you intend. "Invited short talk" or "Invited workshop presentation" might be more accurate. I assume you don't have a lot of these requiring a general description for a section of your CV.

Your advisor had options about who to invite. He wasn't obligated to invite you and trusts that you have something to offer.

However, since he will be writing you letters of recommendation for grad school, I assume, you can ask him what is best here.

In principle, an invited speaker at a conference or workshop is a researcher who has significant experience in the field: it is assumed that their talk is valuable for the participants, that's why they are "invited".

Although you are technically "invited", I would recommend not listing this as an "invited talk" because academics are likely to think that it's an abuse of the term in this case or worse, that it's a lie. To be safe I would just list it as a regular talk.