title: Adding lubridate dates to vector changes timezone and thus date
body: <p>In the R package lubridate, I can easily create a date with the following syntax:</p>
  
  <pre><code>&gt; mdy("5/4/2015")
  </code></pre>
  
  <p>As expected, it produces the following result:</p>
  
  <pre><code>[1] "2015-05-04 UTC"
  </code></pre>
  
  <p>However, if I try to add that very value to an array, it seems to change from UTC to my local time (EDT):</p>
  
  <pre><code>&gt; c(mdy("5/4/2015"))
  [1] "2015-05-03 20:00:00 EDT"
  </code></pre>
  
  <p>Since I don't care about times this wouldn't affect me much except that this results in the date shifting back by 1, as follows:</p>
  
  <pre><code>&gt; day(mdy("5/4/2015"))
  [1] 4
  &gt; day(c(mdy("5/4/2015")))
  [1] 3
  </code></pre>
  
  <p>To me, the act of adding something to an array should not change the value of that something. Am I missing something here, and is there a way to resolve this issue?</p>