I'm not sure about the responses you're getting for the MX record's IP Address, but my queries (on 2/4) do agree that the MX record points to gmail-smtp-in.l.google.com.
My query result points gmail-smtp-in.l.google.com at 173.194.64.26.
When executing a query directly against ns5.pairnic.com I am able to obtain the IP Address stated (216.92.3.110) for the defined MX record (gmail-smtp-in.l.google.com).
The only thing that tells me is that the DNS cache at ns5.pairnic.com is likely corrupted, or stale, or there is a rogue 'A' record for that hostname that ought not be in that DNS server (as you've suggested).
Unfortunately, ns6.pairnic.com also returns that same IP Address, which discredits the idea of a server-specific issue, but suggests that pairnic.com may indeed have invalid data.
As for the actual MX server, quering ns1.google.com directly places gmail-smtp-in.l.google.com at 173.194.64.27.
Changing my DNS source to 8.8.8.8 == google.public.dns-a.google.com puts the gmail server at 173.194.64.27 as well.
Ergo, I gotta agree that the pairnic.com servers are serving up BAD information.
I'm not sure where the 74.125.142.27 is coming from, but a reverse query puts that IP Address at ie-in-f27.1e100.net.