I'm a little confused. Are you saying that we were previously a partnership, and now are electing to be treated as an S-corporation starting in May? Filing a 1065 for the whole year would not make sense. If so, yes, I agree that a short-year 1065 needs to be filed for the short year period (Jan 2014 to April 2014 if calendar).
Make sure you timely elected both the check the box and S-election to begin on May 2014. Be mindful of any Sec- 754 election basis issues that would apply when going from partnership to S-corp. The other partners in this scenario are effectively transferring their member interests to the one partner, and the remaining partner is getting issued stock (likely to be shown as APIC) in the new LLC S-corp.