Audax,
Assuming you have cycled LR, the Ammonia may be stuff on/in the rock that died on transport and transition to your aquarium. You may not even see nitrites spike if the cultures in the LR are strong. Monitor your levels and if ammonia goes to 0 quickly and nitrites stay 0 and nitrates bump up a little, you may be about ready to go.
For my IM 10g, I bought LR and sand from a local reefer and transported it all submerged in his water and used about half his water in my tank. I never saw a cycle.