The only thing left to do regarding your investigation is to go back and speak with the girlfriend. You need to establish what she knew and what she did with that information. You have to decide if there are any charges that you may want to pursue if she was actively hiding the suspect or interfering with your arrest.
Now you need to debrief so you can go over the good, the bad, and the ugly. Although this operation went well, it's important to always ask what could have been done better. Getting everyone's input is essential to building teamwork. You should never miss an opportunity to go over tactics or any applicable policies after an operation, especially if any less experienced officers were involved. Every time you work with such an officer this way you are helping mold the future of the agency. Remember to include any detective, watch commander, and PIO considerations in your wrap-up as well.
Final Thoughts
Warrant service either goes well or it doesn't. There never seems to be an in-between. It's been my experience that by adding a little planning it tends to go better. If there is no exigent circumstance, you should take the time to plan your actions.
Although surprise is always a good tactic, you never really know how it will go until you execute your plan. Dwight Eisenhower, supreme allied commander during WWII, said, "In preparing for battle I have always found that plans are useless, but planning is indispensable." A little structure while maintaining an open mind toward what may happen goes a long way.