The armour resembles one of the ones on display in Tony's office during a scene in the Ultimates.
The big, boxey armour, after all, isn't the first one he's meant to have come up with - He designs that after his epiphany in the mountains, and it's suggested he's developed more before this.
Also, those pointing fingers at Bendis (which is fair, more often than not), note that in issue #27 of Ultimate Spidey, Iron Man was wearing the appropriate armour, and given this is a flashback tale, it's likely to be little more than an old armour.