No problem in the US - not only is there common sense, but there can be a procedure in place to cover it formally, per the 7110.65:
4. When transitioning from terminal to en route control, 3 miles increasing to 5 miles or greater, provided:
(a) The aircraft are on diverging routes/courses, and/or
(b) The leading aircraft is and will remain faster than the following aircraft; and
(c) Separation constantly increasing and the first center controller will establish 5 NM or other appropriate form of separation prior to the aircraft departing the first center sector; and
(d) The procedure is covered by a letter of agreement between the facilities involved and limited to specified routes and/or sectors/positions.