That's not necessarily true in all jurisdictions, as the elements defining degrees of murder are not universal. But, interestingly, in the case of Michigan (which applies here), you may be correct, insofar as a "premediated killing" is construed as a killing performed "in cold blood".

Michigan's statutes indicate that first degree murder includes any willful, deliberate, and premeditated killing. [1] Whereas second degree murder includes all "other kinds" of murder which do not fall under the specifically enumerated conduct rising to the level of first degree murder. [2]

While the second degree murder statute does not expressly describe what circumstances would precipitate those "other kinds" of murder, the statute outlining the scoring system for crimes involving "intent to kill" suggests that second degree murder would be committed where the offender had unpremeditated intent to kill or created a very high risk of death knowing that death was the probable result. [3]

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[1] http://www.legislature.mi.gov/(S(cdcjvuv1er3twxx1crhz3tb3))/...

[2] http://www.legislature.mi.gov/(S(cdcjvuv1er3twxx1crhz3tb3))/...

[3] http://www.legislature.mi.gov/(S(cdcjvuv1er3twxx1crhz3tb3))/...