I see a malformed packet in Wireshark from a Google IP address on port 2400 using R-GOOSE protocol, what could this be?

edit

This might be a greedy heuristic grabbing a frame that doesn't belong to it.
The disssector looks at a single byte to decide if the protocol is for it.

packet-goose.c:

#define OSI_SPDU_GOOSE    0xA1 /* GOOSE */
...
    /* Is it R-GOOSE? */
    spdu = tvb_get_guint8(tvb, 0);
    if (spdu != OSI_SPDU_GOOSE) {
        return FALSE;
    }

It would help if you could provide a sample capture that contains the full packet and a few before it for context.